diff --git a/tools/jenkins/run_jenkins.sh b/tools/jenkins/run_jenkins.sh
index a95819af601721bc5c0980f9bba65d98158b7df3..a754015f4003fbcdbd5d52ebdb99bbbb87b048e7 100755
--- a/tools/jenkins/run_jenkins.sh
+++ b/tools/jenkins/run_jenkins.sh
@@ -41,9 +41,17 @@ if [ "$platform" == "linux" ]
 then
   echo "building $language on Linux"
 
+  if [ "$ghprbPullId" != "" ]
+  then
+    # if we are building a pull request, grab corresponding refs.
+    FETCH_PULL_REQUEST_CMD="&& git fetch $GIT_URL refs/pull/$ghprbPullId/merge refs/pull/$ghprbPullId/head"
+  fi
+
   # Run tests inside docker
   docker run grpc/grpc_jenkins_slave bash -c -l "git clone --recursive $GIT_URL /var/local/git/grpc \
-    && cd /var/local/git/grpc && git checkout -f $GIT_COMMIT \
+    && cd /var/local/git/grpc \
+    $FETCH_PULL_REQUEST_CMD \
+    && git checkout -f $GIT_COMMIT \
     && git submodule update \
     && nvm use 0.12 \
     && rvm use ruby-2.1 \